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Slideshow

Introduction

From the beginning of the establishment of the department of physics in 1967, the department tried to conform all the educational programs to creditable departments of physics around the world. We see that the number of graduate students published theses in international journals exceed one hundred. The faculty include leaders in major areas of physics in Iran. Today more than 350 undergraduates and 250 plus graduate students are being supervised by 31 faculty members, sometimes invited professors from inside or outside of the country.

In this talk I review a covariant generalization of Einstein's general relativity which allows the existence of a term proportional to T_{\alpha\beta} T^{\alpha\beta} in the action functional of the theory ( T_{\alpha\beta} is the energy-momentum tensor). This simple generalization leads to interesting consequences in the early universe. Applying this theory to a homogeneous and isotropic spacetime, we find that there is a maximum energy density ρ_{max}, and correspondingly a minimum length a_{min}, in the thermal history of the universe. This means that there is a bounce at early times, and this theory avoids the existence of an early-time singularity. Also I review the possible consequences of this theory in the dynamics of compact objects like Neutron stars. More specifically I discuss the mass-radius relation for Neutron stars in this model.